Removal of Tetracycline Antibiotics from Dairy Farm Wastewater by Electrocoagulation Using Iron Electrodes

Veterinary antibiotic residues in wastewater discharged from livestock facilities have become an environmental issue. In this study, the removal of veterinary antibiotics by electrocoagulation was investigated for dairy farm wastewater treatment. Three tetracycline antibiotics (TCs) and cefazolin (CEZ), a cephalosporin antibiotic, in synthetic wastewater were electrochemically coagulated using iron electrodes under a constant current. The removal rates of the TCs were higher than 80% after electrocoagulation and gravity settlement. The specific properties of TCs enable them to coordinate to metal ions. In contrast, the electrocoagulation showed a lower removal rate of 2.5% for CEZ which lacks of interaction with metal ions. The results indicated that higher removal of TCs was achieved by this iron–tetracycline interaction. The removal rates of oxytetracycline (OTC) in dairy farm wastewater were increased with increasing electric charge and reached more than 88% at different temperatures. The isothermal data obtained from OTC in the synthetic wastewater showed that the Langmuir model was a better fitting model than the Freundlich model, thus, indicating the applicability of monolayer coverage. The results showed that electrocoagulation is an effective method for the removal of antibiotics that are able to coordinate with the metal ion.